In point-to-multipoint networks—such as the passive optical network (PON)—optical burst, signals (databursts) are transmitted in time-division multiplex method from user devices (ONTs) to a central node (OLT). In this context, the carrier frequencies can be slightly different from burst signal to burst signal especially when inexpensive lasers are used. Between the user devices and the receiving device of the central node or, respectively, in the receiving device of the central node, at least one optical amplifier is arranged which adds optical noise, the so-called “amplified spontaneous emission”. To obtain from the demodulator a data signal which is as free of interference as possible, it is necessary to filter the received optical signal with as narrow a bandwidth as possible in order to reduce the optical noise as far as possible.
In patent application GB 2315 939 A, a fiber amplifier is described which is followed by a tracking filter for reducing the noise. The amplifier described is suitable for use in point-to-point connections. In point-to-multipoint connections, however, this would assume the presence of precisely identical carrier frequencies for all transmitting devices of the user devices. This again necessitates frequency-stabilized or frequency-controlled lasers which, however, cost considerably more than normal lasers.